Summary

The aim of this work was to obtain a number of complete soluble compost extracts rich in micronutrients, which can safely be used for fertigation through modern irrigation systems in organic farming system. Evaluation of their effects was conducted on potato crop var. Draga and soil fertility. During the extraction experiment two different composts (Farm compost and Commercial compost) were treated with water to obtain following dilution ratios: 1:5, 1:10, 1:20. Most chemical parameters of the compost extracts generally reflect the chemical composition of the starting material. These six dilutions were applied during the growing season. The control shows the highest tuber yield (22.1 tons/ha) followed by FC20 treatment (21.03 tons/ha). The number of tubers per plant was not significantly different between treatments, meanwhile the leaf surface was the lowest exactly in the treatment FC20 (1.941cm²) and control (1.250cm²) which had the highest yield. Phytotoxicity experiment was conducted to show if compost extracts have any phyto-toxic effect applied during seeds plantation. Seeds of durum wheat (Triticum durum) were treated with different compost extract dilutions and results revealed that only CC10 and CC20 dilutions achieved germination index 104.7% and 81.44%, meanwhile all the other concentrations showed phytotoxic effect. Analysis of soil organic matter and available nutrients showed that the major changes observed, as a function of the applications and affecting somewhat the soil fertility, were organic C, K and P content. The results are discussed in relation to significant differences between six dilutions obtained from two composts.